Casing for a drug delivery system



FIG. 1 is a front elevational view of a casing for a drug delivery system embodying our new design;

FIG. 2 is a right end elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left end elevational view thereof; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for casing for a drug delivery system, as shown. 